CRS-17 Dragon returns home – NASASpaceFlight.com

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SpaceX's CRS-17 Dragon spacecraft completes the mission-end mission phase after leaving the International Space Station (ISS) on Monday. The Dragon output of the Space Station Remote Manipulation System (SSRMS) was held at 16:00 UTC. A crash in the Pacific Ocean is scheduled for 21:10 UTC Monday.

The CRS-17 Dragon was launched last month on the Falcon 9 B1056.1. The recall also came back without problem, which allowed him to be prepared for a future mission.

The CRS-17 mission delivered 338 kilograms of space station crew supplies, 357 kilograms of computer equipment for the US and international segments of the station, 75 kilograms (165 pounds) of computer, 10 kilograms (22 pounds) ) equipment to support the EVA and 11 kilograms (24 lb) of material used on behalf of the Russian Federal Space Agency, Roskosmos.

The Dragon cargo includes components for the new space station water storage system, filters for a new waste management system, cable harnesses and depressurization indicators that will be used for future flights commercial crews, as well as the POLARS system which will facilitate the transport of scientific experiments at low temperatures. .

The unpressurized chest of Dragon contains material that will be mounted outside the space station. This includes the OCO-3 (Orbiting Carbon Observatory 3) payload, which will use three spectrometers to measure the density and distribution of carbon dioxide in the Earth's atmosphere.

The Vault also contained the Houston 6 Space Test Program (STP-H6), a set of eight technology development and demonstration payloads for the US Air Force (STP) space test program. STP-H6 includes experiments that will test ionospheric and plasma search instruments, demonstrate computing resources for in-orbit image processing, validate the use of modulated X-rays for communications, and test future satellite systems.

After the two payloads have been removed for installation on the ISS, the robotic assets

Before the return trip, Dragon was crowded and the hatch closed. The robotic ground controllers then used the robotic arm to detach Dragon from the Harmony module port facing the Earth, to maneuver Dragon into the release position.

Dragon was decommissioned by the Space Station Remote Manipulation System (SSRMS) at 12:35 UTC before being released from the robotic arm at 16:00 UTC.

Once the LEE snares were released, the SSRMS was removed from Dragon while the craft held its position at the 10 meter mark.

Once the station arm was cleared at a safe distance, Dragon performed a series of three small burns from propellers that move the capsule along the R-bar (radial vector) and away from it. from the International Space Station to the Earth (viewed in relation to ISS Orientation and Dragon Movements to the Earth).

During the initial phase of departure, Dragon was under the control of its own programming, the crew of the station and the Houston Mission Control Houston controllers for NASA having the main control of the spacecraft.

When Dragon pushed the R-Bar down, the larger of the three thruster starts conferred enough Delta Velocity (Delta-V) changes to Dragon to push him out of the approach ellipsoid .

ISS starting area

The approaching ellipsoid is an oval-shaped area surrounding the International Space Station, 4 km by 2 km, which stretches for 2 km forward and 2 km back from the north. ISS along the velocity vector (V-Bar) and 1 km above and 1 km below the space station. Station along the R-Bar.

Once Dragon cleared the approaching ellipsoid 1 km below the ISS, the vehicle's main control went from NASA controllers to SpaceX controllers in Hawthorne, California.

Dragon drove several hours of free flight as Mission Control SpaceX controllers who prepared the vehicle for the end of his mission.

This included closing the Dragon Control and Guidance Door (GNC), creating a perfect heat seal around the entire Dragon for the entrance.

SpaceX flight controllers in Hawthorne, California, ordered Draco Draco's propellers to fire for 12 minutes and 53 seconds – retrograde – in the desorbite effect that had allowed Dragon to come out of its orbit to return to Earth.

Following the desorption burn, the umbilicals between Dragon and its outer chest were cut before the trunk was separated from the Dragon itself.

Dragon then placed his heat shield in front, in anticipation of the Entry Interface (IE), at which point Dragon reached the first traces of the Earth's upper atmosphere.

Re-entry of the dragon, via SpaceX

Once Employment Insurance came into being, Dragon's Thermal Protection System (TPS) protected it from hot back-to-back temperatures as the air molecules around Dragon instantly heated up and turned into plasma under friction. created by the high speed of Dragon.

Dragon's main heat shield, called PICA-X, is based on an exclusive variant of NASA's PICA (Phenolic Impregnated Carbon Ablator) material and is designed to protect Dragon during atmospheric reentry.

PICA-X is robust enough to protect Dragon not only on ISS return missions, but also on high-speed returns from lunar and Martian destinations.

Unlike the Dragon capsule, the dragon's trunk is destructively consumed in the Earth's atmosphere.

Once safely through the plasma phase of the comeback, Dragon's drug parachutes were deployed, followed by the main chutes designed to facilitate the recovery of the vehicle.

Dragon Splash

The recovery is obtained by three main recovery vessels positioned near the place of return of Dragon. The main recovery vehicle had already set sail earlier in recent days.

Rapid Recovery Vessels deployed to begin collecting Dragon parachutes, recovery of the capsule itself being provided by major salvage assets.

Dragon paratroopers-assisted splashing usually takes place 410 km southwest of Long Beach, California.

It will take about two days for Dragon to be brought back to the port of Los Angeles to unload his cargo cache and scientific experiments.

The ISS crew spent most of the second half of Dragon's stay in their pressurized capsule of key elements to be returned to Earth, including many time-sensitive experiments, which will be the first to to be removed.

Dragon will eventually travel to the SpaceX test center in McGregor, Texas for the complete removal of his cargo.

CRS-18 is the next Dragon Mission on the ISS, currently scheduled for July.

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